• Title/Summary/Keyword: 체류 시간

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Variation in Residence Time and Water Exchange Rate by Release Time of Pollutants Over a Tidal Cycle in Masan Bay (조석 주기별 오염물질 방출에 따른 마산만의 체류시간 및 해수교환율 변화)

  • Park, Sung-Eun;Lee, Won-Chan;Hong, Sok-Jin;Kim, Hyung-Chul;Kim, Jin-Ho
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.14 no.4
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    • pp.249-256
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    • 2011
  • Lagrangian particle transport model coupled with the EFDC have been performed to estimate the residence time and water exchange rate by release time of pollutants over a tidal cycle in Masan Bay. The modelled residence time for the whole bay was about 40 days, ranging from less than 20 days in the southern parts of Budo, to over 100 days in the upper parts of Somodo. The spatial difference of residence time was controlled by tidal residual currents and the distance to the bay channel. The area mean residence time during spring and neap tides was estimated to be about 36 days and 42 days, respectively. The time required for 30% exchange of water was calculated as ranging from 65 to 105 days by release time of pollutants.

A Numerical Prediction of Residence Time According to Freshwater Influx in Enclosed Bay (담수유입에 의한 폐쇄성 내만의 물질체류시간 수치예측)

  • Kim, Jin-Ho;Lee, In-Cheol
    • Journal of the Korean Society of Marine Environment & Safety
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    • v.17 no.4
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    • pp.339-343
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    • 2011
  • This study is to examine the effect of freshwater influx on residence time to understand a long-term material transportation in enclosed bay. To predict the residence times of the coastal water in Masan bay, we were carried out the numerical simulations by using a EFDC model to simulate seawater circulation and particle tracking. The average residence times of Masan bay obtained from the particle release simulations under the condition to neglect a freshwater influx were estimated to be about 110 days in northern part of the bay to near Dotseom, 40 days in around Modo and 20 days in Budo to open sea. However, the average residence times under the condition consider with freshwater influx decreased about 81 days in both Region 1(northen Masan bay to near Dotseom) and Region II (Dotseom to Modo), but the Region III(Modo to Budo) and Region IV(Budo to open sea) incresed about 58 days and 17 days, respectively.

Effects of Nutrient Concentration and Hydraulic Retention Time on the Removal of N and P by Phragmites japonica Steudel (영양염류의 유입농도와 수리학적 체류시간에 따른 달뿌리풀(Phragmites japonica Steudel)의 질소와 인 제거능)

  • 신정이;차영일
    • Korean Journal of Environmental Biology
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    • v.17 no.2
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    • pp.153-158
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    • 1999
  • Uptakes of N and P by Phragmites japonica Steudel. are determined in continuous flow tanks as a function of hydraulic retention time (HRT, days) and nutrient concentration (NC). Results show that the uptake was higher at shorter HRT and higher nutrient concentration, and the regression equations were estimated. Mean above ground biomass of Phragmites japonica in the middle reaches of Sagimak stream was 335.92 g/$m^2$, and estimated uptake by this vegetation were 7.31~20.15 NH$_4$-N, 31.15~95.84 NO$_3$-N, and 4.09~11.48 PO$_4$-P mg/$m^2$/day in Sagimak stream, respectively when HRT was 1~5 days. According to this study, it is concluded that Phragmites japonica Steudel. are suitable for water quality improvement of stream through nutrient uptake at short HRT and high concentration.

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Effect of Retention Time on the Removal Efficiency in Grassed Swale (체류시간이 식생수로 저감효율에 미치는 영향)

  • Paek, Seoungbong;Gil, Kyungik
    • Journal of Wetlands Research
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    • v.16 no.3
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    • pp.371-381
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    • 2014
  • Recently the water quality management policy gives priority to management the point source. Non-point pollution source is difficult to comprehend because those don't have certain outflow point and emission. There are many development and research about BMPs for manage the Non-point pollution source. Various methods of removal efficiency are presented for assessment of Best Management Practices (BMPs). In this study, retention time have effect on removal efficiency based on monitoring results of Grassed Swale is studied. Also, Compare a difference according to various methods of Grassed Swale removal efficiency. The result of removal efficiency analysis depending on retention time of Grassed Swale, removal efficiency is higher as retention time increases. To obtain a stable removal efficiency of Grassed Swale, retention time of Grassed Swale should be secure.

Material Budgets in the Youngsan River Estuary with Simple Box Model (영산강 하구해역에서의 단순 박스모델에 의한 물질수지)

  • Lee, Kyeong-Sig;Jun, Sue-Kyung
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.12 no.4
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    • pp.248-254
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    • 2009
  • Budgets of fresh water, salt, DIP and DIN in the Youngsan river estuary were estimated seasonally in order to clarify the characteristics of material cycling and flux of nutrients with a simple box model. Inflow volumes of freshwater into system was approximately $36.481{\times}10^6{\sim}663.634{\times}10^6m^3/month$ and existing water mass of freshwater in system calculated by salt budget was approximately $2.515{\times}10^6{\sim}5.812{\times}10^6m^3$. Mean residence time of freshwater was calculated to be about 0.26~2.03 day. water exchange $1,248{\times}10^6{\sim}9,489{\times}10^6m^3/month$ assumed with salinity between estuary and adjacent ocean. Inflow mass of DIN and DIN were approximately 76.63~1,149.91 ton/month and 2.91~61.22 ton/month, respectively. Residence times of DIP and DIN were calculated to be 0.45~1.10 day and 0.28~1.92 day, respectively. The ratio of water residence time versus DIP, DIN residence time was calculated that freshwater residence time was longer than DIP, DIN residence time except for summer season. Thus, We assume that circulation of Nutrients in the system will happen rapidly except for summer season. Specially DIP in Winter could assume to outer input source existence because of seawater inflow in system and high DIP concentration in open sea.

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Residence Time Variation by Operation of Sihwa Tidal Power Plant in Outer Sea of Sihwa Lake (시화호 조력발전소 운영에 의한 시화호 외측 해역에서의 체류시간 변화)

  • Bae, Youn Ho;Yoon, Byung Il;Seo, Chang Hoon;Park, Sung Jin;Bang, Ki-Young;Kwon, Hyo-Keun;Woo, Seung-Buhm
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.29 no.5
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    • pp.247-259
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    • 2017
  • Numerical model with LPT (Lagrangian Particle Tracking) module was used to understand the variation of residence time in the outer sea of the Sihwa lake result operating from the Sihwa tidal power plant. Numerical model was composed in order to investigate the spatial distribution characteristics, the average residence time in each area was calculated by dividing the outer sea area of Sihwa lake into 4 areas. The average residence time of the areas appeared to be increase as it entered the areas located in the inner bay (13 days) from the area located in most outer sea (3 days) both before and during operation. Variation of average residence time by areas were increased in the area that was located in the most outer sea of during operation compared to before operation, and decreased in the other area. Artificial discharges from tidal power plant induces particle traps in the formation of vortex in the area located in the most outer seas, entrainment in the remaining areas, which affects variation in residence time. In other words, the jet flow generated during drainage and the change in the residence time due to the vortex and entrainment action indicate the increase horizontal mixing of water in the outer sea and in the inner bay.

Ammonia Removal by using RBC in Recirculating Aquaculture System (RBC를 이용한 양어장수 암모니아 제거)

  • KIM Byong-Jin;LIM Sung-Il;SUH Kuen-Hack
    • Korean Journal of Fisheries and Aquatic Sciences
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    • v.31 no.5
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    • pp.622-630
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    • 1998
  • Rotating Biological Contactor (RBC) was tested for the removal of total ammonia nitrogen (TAN) by using simulated aquaculture system. RBC performance was evaluated by controlling revolution rate of disk and hydraulic residence tile (HRT). The optimum revolution rate of disk was 4 rpm, As HRT of RBC was increased, TAN removal efficiency of RBC and TAN concentration of rearing water were increased. HRT for maintaining lowest TAN concentration of rearing water was 9.5 minutes and at that condition TAN concentration of rearing tank was $1.03 g/m^3$

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Estimation of material budget for Keum river estuary using a Box Model (BOX 모델을 이용한 금강 하구해역의 물질수지 산정)

  • Kim Jong-Gu;Kim Dong-Myung;Yang Jae-Sam
    • Journal of the Korean Society for Marine Environment & Energy
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    • v.3 no.4
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    • pp.76-90
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    • 2000
  • The estimation of material cycle of pollutants is necessary for the environment management in coastal zone. Model for material budgets are useful tools to understand the phenomena of natural system and to provide an insight into the complex processes including physical, chemical and biological processes occuring in natural system. Budgets of fresh water, salt and nutrients were estimated in order to clarify the characteristics of seasonal material cycle in Keum river estuary. Inflow volumes of freshwater into system was approximately 1.014×10/sup 8/~12.565×10/sup 8/m³/month and discharge in Keum river has occupied 99.7% of total freshwater. Seasonal variations of freshwater volume in the system were found to be very high in the range of about 4 ~ 14 times due to rainfall in summer season. Existing water mass of freshwater in system calculated by salt budget was approximately 0.339×10/sup 8/~0.652×10/sup 8/m³. Mean residence time of freshwater was calculated to be about 1.6~10.0day, and exchange time was calculated to be about 2.2~11.9day. Mean residence time was short as 1.6day in summer due to precipitation, and long as 10.1day in winter due to a drought. Inflow masses of DIP and DIN were approximately 5.57~32.68ton/month and 234.93~2,373.39ton/month, respectively. Seasonal inflow mass of DIP was larger than the outflow mass except for summer season. Thus, we postulate that accumulation of DIP in the system will happen. Residence times of DIP and DIN were calculated to be 1.1~6.4day and 1.8~10.9day, respectively. The ratio of water residence time versus DIP, DIN residence time was calculated to be 0.39~2.31 times and 0.83~1.13 times, respectively.

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The Effect of Hydraulic Retention Time on The Power Density in a Horizontal Flow Microbial Fuel Cell (수평 흐름형 미생물 연료전지에서 수리학적 체류시간이 전력수율에 미치는 영향)

  • Lee, Chae-Young;Park, Su-Hee;Woo, Jeong-Hei;Yoo, Kyu-Seon;Jeong, Jea-Woo;Song, Youn-Chae
    • Journal of the Korea Organic Resources Recycling Association
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    • v.19 no.1
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    • pp.109-114
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    • 2011
  • This study was conducted to investigate the effect of hydraulic retention time(HRT) on the power density in a horizontal flow microbial fuel cell(MFC) reactor. When HRTs were 15min, 30min, 60min and 180min, maximum power densities were $24.7mW/m^2$, $27.3mW/m^2$, $22.8mW/m^2$ and $17.2mW/m^2$, respectively. The highest power density was obtained at HRT of 30min. It was 59% improvement when compared to the power density at an HRT of 180min. When HRT was increased, COD removal rate increased whereas the coulombic efficiency remained constant. The result shows that the optimal performance of the horizontal flow MFC reactor could be achieved at HRT of 30min.

Study on the Improvement of Nitrate Removal Efficiency in Multi-Step Electro-chemical Process (전기화학적공정에서 질산성질소 제거효율 향상에 관한 연구)

  • Sim, Joo-Hyun;Kang, Se-Han;Seo, Hyung-Joon
    • Journal of Korean Society of Environmental Engineers
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    • v.30 no.2
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    • pp.155-160
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    • 2008
  • In this study, the nitrate removal efficiency was examined under a variety of operating conditions, such as different doses of the reducing agent, different electrode types, different HRTs(hydraulic retention times), and different current densities, using the multistep electrochemical process. The nitrate removal efficiency increased and the input energy decreased when the reducing agent was used, and almost no difference was found between the electrode types in terms of their nitrate removal efficiency and current efficiency. So that the Zn reducing agent could be recovered, though, the B-type electrode was chosen(step 1: Pt-Zn; step 2: Pt-Zn; step 3: Pt-Zn; step 4: Pt-Zn). HRT experiments were carried out on constant electric current density unrelated HRTs and various electric current density related HRTs: the constant amount of electric current per unit volume. As a result, HRT and the electric current density caused concentration polarization and the lack of an applied current. That is to say,the lower the HRT, the greater the decrease in concentration polarization and in the amount of applied current per unit volume. Therefore, optimal conditions were found through the experiments that were conducted on HRT and electric current density. When a spacer was installed in the process, the nitrate removal efficiency and energy efficiency increased even more because the diffusion likewise increased.